Interview subjects in "Nobodies to Somebodies: How 100 Great Careers Got Their Start," by Peter Han (Portfolio, $22.95).

Bill Bradley, former U.S. Senator (New Jersey), started out as a basketball player for the New York Knicks, but during the offseason, the Rhodes Scholar would teach school in Harlem and even worked in Washington, D.C., under then-Rep. Donald Rumsfeld.

Slade Gorton, former U.S. Senator (Washington). The "impecunious Yankee Republican Protestant," actually born and raised in Illinois, arrived here on a one-way bus ticket with $300 in his pocket. The region's political openness and small-town sensibilities provided the environment he needed to flourish.

Wendy Kopp, founder and CEO of Teach for America, wasn't thrilled about taking a conventional public-policy job right out of college. Instead, she really wanted to follow her passion to teach in low-income communities, so in 1989, after "descending into a funk," she decided to establish her teacher corps, comprising recent graduates who were also interested in that goal.

Nadine Strossen, ACLU president, said practicing law shaped her more than academics did: "I wanted to get out and get the experience. ... I loved being a lawyer, but not going to school to become one."

Tom Clancy, novelist, started his career as an insurance agent and didn't achieve success as a writer until he reached his 40s.